1. Field of the Invention
The present invention relates generally to mulches and erosion control, and more particularly to a blended mulch product for making an erosion control medium for reducing erosion of a ground surface and a methods of making same.
2. Background Art
For large-scale revegetation work such as occurs during highway construction, large residential or commercial building construction, mine or landfill reclamation, hydraulic application of mulch is an efficient aid to control soil erosion and aid in revegetation. In general, existing mulches are typically placed or left on or near a soil surface to protect it from erosion and to aid in the establishment of vegetation. Once applied to the soil surface, the mulch forms a mat product to aid in erosion control and the revegetation process.
In order to apply mulch to a soil surface, traditionally, thermomechanically-refined or mechanically-refined virgin or recycled wood is added to water to form a wet slurry. Typically, the slurry is formed within a large tank equipped with mechanical agitators or circulation pumps (e.g. in a hydroseeder tank). When made into a slurry the mixture is pumped through an outlet hose or cannon. Natural or synthetic tackifiers are optionally added by the operator to the tank to improve the viscosity of the slurried mixture, to reduce friction of solid materials in the pump, to prevent plugging of the pumps and to aid in adhering the mulch to the underlying surface. However the addition of the tackifiers too quickly to the slurry can create “fisheyes” within the tackifier, resulting in reduced effectiveness of tackifier adhesion, decreased viscosity and potential plugging of hose nozzles. In addition, incorrect quantities of mulch components will compromise the performance of the product especially when the mulch is applied on steep slopes. In order to provide an alternative approach, certain pre-blended mulch products have been introduced into the marketplace.
In U.S. Pat. No. 5,476,711 a fiber blending system is described including an apparatus and method of forming a mat of cellulosic fibers and synthetic fibers. According to U.S. Pat. No. 5,476,711, the method disclosed includes the steps of fiberizing cellulosic material into cellulosic fibers in a fiberizer, volumetrically metering a metered amount of synthetic fibers, and injecting the metered amount of synthetic fibers into the cellulosic fibers. The cellulosic fibers are blended with the metered amount of synthetic fibers in a blending chamber to form a fiber blend. The fiber blend is dispersed through a fiber disperser having apertures of a pre-selected size and shape to provide a dispersed fiber blend. A third type of fiber may also be mixed with the dispersed fiber blend. The dispersed fiber blend is collected as a mat on a fiber collector to provide a mat of blended cellulosic and synthetic fibers. The mat may be thermobonded by a thermobonder and sandwiched between a facing sheet and a backing sheet.
U.S. Pat. No. 5,942,029 describes a water absorbent fiber mulch made from natural and crimped, synthetic fibers that are intimately mixed together to form the fiber mulch. In U.S. Pat. No. 5,942,029 the fiber mulch is a mechanically bonded, open weave accomplished by entanglement of the crimped synthetic fibers with one another and with the natural fibers to hold the mulch together in a matrix which is sufficiently open to allow air to pass through, and seedlings to grow up through. A water absorbent polymer-based material is dispersed throughout the fiber mulch to increase its water absorption capacity. Similar mulch products are found in U.S. Pat. Nos. 5,779,782 and 5,741,832.
Notwithstanding the mulch products in the field, there remains a need in the art for a mulch product having desirable properties and a substantially homogenous composition.